Driving workload estimation

ABSTRACT

A method for estimating workload placed on the driver of a vehicle. The method comprises receiving workload estimation data. A driving workload estimate is calculated in response to the workload estimation data. The driving workload estimate is indicative of current and previously occurring conditions. The driving workload estimate is then output.

BACKGROUND OF THE INVENTION

The present disclosure relates generally to driving workload estimationand in particular, to a method of assessing the marginal effect ofvehicle conditions, environment conditions and current task conditionson the driver of a vehicle.

Vehicles, such as automobiles, generally feature one or more displays toprovide locally obtained information related to a current state of thevehicle. The display is positioned within the vehicle such that a driverof the vehicle may view information while driving the vehicle. Forexample, the display may provide information on a windshield, adashboard or a steering wheel. Each display may contain one or morewindows. Locally obtained information, such as the speed of the vehicle,the direction traveled by the vehicle, the outside air temperature,whether the air conditioner is in use, whether the hazard light is on,fuel status of the vehicle, and the like, may be provided in thesewindows. In addition, information can be collected from vehicle sensorsand used to create vehicle status and maintenance messages for displayin the windows. These messages can include information such as “windowwasher fluid low” and “check tire pressure.”

The current displays in vehicles are capable of providing differenttypes of media from a variety of sources. The display may provide audio,text, graphic images, and/or video (e.g., night vision display).Additionally, the display may provide information from various databasesand remote servers using a wireless network. For example, traffic and/orweather alerts may be communicated through any of the display meansmentioned above. In addition, smart advertising may be transmitted tothe display to inform the driver of a nearby restaurant or store.Providing all of these types of information and media may be helpful tothe driver but providing it without considering the current drivingsituation may result in increased driver workload, driver distractionand/or decreased driving performance.

BRIEF DESCRIPTION OF THE INVENTION

The above discussed and other drawbacks and deficiencies of the priorart are overcome or alleviated by a method for estimating workloadplaced on the driver of a vehicle. In an exemplary embodiment, themethod comprises receiving workload estimation data. A driving workloadestimate is calculated in response to the workload estimation data. Thedriving workload estimate is indicative of current and previouslyoccurring conditions. The driving workload estimate is then output.

In another aspect, a system for estimating workload placed on the driverof a vehicle comprises a network and a microprocessor in communicationwith the network. The microprocessor includes instructions to implementa method. The method comprises receiving workload estimation data fromthe network. A driving workload estimate is calculated in response tothe workload estimation data. The driving workload is indicative ofcurrent and previously occurring conditions. The driving workloadestimate is then output.

In still another aspect, a computer program product for estimatingworkload placed on the driver of a vehicle comprises a storage mediumreadable by a processing circuit and storing instructions for executionby the processing circuit for performing a method. The method comprisesreceiving workload estimation data. A driving workload estimate iscalculated in response to the workload estimation data. The drivingworkload estimate is indicative of current and previously occurringconditions. The driving workload estimate is then output.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the exemplary drawings wherein like elements are numberedalike in the several FIGURES:

FIG. 1 is a block diagram of an exemplary system for performing drivingworkload estimation;

FIG. 2 is a table of exemplary driving workload estimate inputs; and

FIG. 3 is a table of logical operands associated with driving workloadestimation in an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein is a method of driving workload estimation. Brieflystated, the method utilizes vehicle data, environment data and currenttask data to estimate the workload placed on the vehicle driver. Aconditional model of the driver's workload (herein identified as drivingworkload) is developed by assessing the marginal effect of the vehicle,environment and current tasks on the driver. Multiple levels or statesof the driving workload are estimated by workload estimation software.In an exemplary embodiment, the estimated workload states include aninstantaneous workload estimate, an intermediate workload estimate andan overall workload estimate. Alternatively, the system can utilize asingle workload estimate, provided that some method of accounting forthe lingering impact of events and conditions that are no longeroccurring is taken into account by the workload estimate. Theseestimated workload states are output and can be sent to a vehicleinformation management system to aid in controlling the messages beingsent and the functionality available to the operator of the vehicle.

FIG. 1 is a block diagram of an exemplary system for performing drivingworkload estimation. Vehicle data 104, environment data 106 and currenttask data 108 are input to a driving workload estimator 102. The drivingworkload estimator 102 includes application code for creating aninstantaneous workload estimate 110, an intermediate workload estimate112 and an overall workload estimate 114. In an exemplary embodiment,the driving workload estimator 102 is located on a microprocessorcontained in the vehicle. The microprocessor may be dedicated toperforming driving workload estimator 102 functions or, alternatively,the microprocessor may include application code for performing othervehicle functions along with the driving workload estimator 102functions. In addition, storage space for intermediate applicationresults as well as application inputs and outputs can be located on themicroprocessor or located on an external storage device accessible bythe microprocessor.

Vehicle data 104 is internally generated and is received from sensorslocated inside the vehicle. Vehicle data 104 can include informationsuch as vehicle speed, cruise control state, turn signal status,traction control status (TCS), antilock braking system (ABS) status,vehicle stability system data, powertrain data, steering wheel angle,brake pedal position and throttle pedal position data. Powertrain datacan include information such as revolutions per minute (RPM), spark dataand fuel data. Environment data 106 can include external lightsensor/headlamp status data, wiper status, defroster status, outside airtemperature (OAT), global positioning system (GPS) data, time of day,and enhanced digital maps. Current task data 108 includes data such asradio information (e.g., is manipulation occurring) and phoneinformation (e.g., is the phone active). In addition, driveridentification input to the driving workload estimator 102 can be usedto tailor the workload estimates to a particular driver of the vehicle.Additional input can include driver monitoring data and input that isscalable to the vehicle sensor set and the equipment package (e.g.,navigation, imbedded cell phone). Driver monitoring data includes theability for the driver, or the vehicle system to revise the drivingworkload estimate. Additional input data can also include informationfrom an object detection and warning and/or lane sensing application orsensor. Examples include forward collision warning (FCW) data, sideobject detection (SOD) data, lane departure warning (LDW) data and rearcollision warning (RCW) data. Further input to the driving workloadestimator 102 can include infotainment and telematics system status;speech interface status and diagnostics data; and adaptive cruisecontrol (ACC) system data.

The specific inputs to the driving workload estimator 102 can varybetween implementations depending on the input data available in aparticular vehicle and the requirements of a particular implementation.A network can be used to obtain the data and the network can be internalto the vehicle or the network can provide access to information outsidethe vehicle. Any information that can be sensed, measured or inputthrough an interface (e.g., wireless network) can be used as input tothe driving workload estimator 102. Environment data 106 can be expandedto include information such as vehicle location data; external vehiclelocation data; traffic information both present and predicted; andweather information both present and predicted. As depicted in FIG. 1,three workload estimates are output from the driving workload estimator102. The workload estimates are updated on a periodic basis and includenumeric values that reflect relative workload levels. The workloadestimate can be relative to a starting state such as clear driving atnormal speed or driver workload when the vehicle is stationary. In analternate embodiment, data in addition to the numeric values may beincluded in the workload estimates.

The instantaneous workload estimate 110 is based on a short-term timeframe (e.g., the preceding zero to three seconds). For example, a turnsignal coupled with a particular steering wheel angle may indicate thatthe vehicle is turning. The act of turning would have an impact on theinstantaneous workload because it will add to the current drivingworkload and is generally completed in a few seconds. The intermediateworkload estimate 112 is a workload based on an intermediate timeinterval (e.g., twenty seconds to one minute, three seconds to threeminutes, three seconds to ten minutes). The intermediate workloadestimation will carry a declining balance input on workload estimatesfor recent events. For example, if the input data indicates that thedriver has just merged into traffic or that the ABS brake system isactivated, the intermediate workload estimate 112 would reflect theseevents for a specified intermediate time interval. This may beimplemented by having the estimator initiate a sub-routine that causesthe workload estimate to remain above the starting state due to the factthat the effect of an ABS event does not end as soon as the ABS stopsbeing activated. An event that affects the intermediate workloadestimate 112 includes some recovery time for the driver and this isreflected in the length of time that the workload estimate continues toreflect the occurrence of the event.

The overall workload estimate 114 includes long term workload or totalworkload accumulated during an ignition cycle (e.g., from three minutesand up, ten minutes and up, entire ignition cycle). For example, thelength of time that the driver has been operating the vehicle can befactored into the overall workload estimate 114. In an exemplaryembodiment, each workload estimate is associated with from three to onehundred workload level values. In an alternate embodiment, hundreds orthousands of workload level values may be associated with each workloadestimate.

The input data depicted in FIG. 2 can be utilized by a driving workloadestimator 102 to calculate the driving workload estimate as a functionof vehicle data 104, environment data 106 and current task data 108.Referring to the vehicle data 104 in FIG. 2, the value of vehicle speed202 can be calculated based on the current speed of the vehicle andwhether the driver is accelerating or decelerating. The value of turnsignal status 204 can be determined based on whether the turn signal isactivated. The value of ABS/TCS/ stability system data 206 can becalculated from sensor data gathered from dynamic vehicle controls suchas the wheel speed sensors. The steering wheel angle data 208 isdetermined by sensors capable of determining the rate of vehicleturning. Brake and throttle pedal position data 210 can be determined bythe data gathered from sensors such as the throttle position sensor(TPS) and brake pedal switch or sensor. The value of engineRPM/spark/fuel data 212 (powertrain data) can be calculated from enginemanagement sensors and data (e.g., the TPS).

Referring to the inputs relating to environment data 106 in FIG. 2, thevalue of headlamp status 214 can be determined by either the externallight sensor or by data from the headlamp controls. The value of wiperstatus 216 can be determined by either a rain sensor or the wipercontrols. The value of defroster status 218 can be determined by thedefroster controls. The outside air temperature (OAT) data 220 can bedetermined by a sensor dedicated to that purpose. Global positioningdata 222 is determined by accessing data from the global positioningsystem within the vehicle network. Time of day 224 is determined fromthe clock data within the vehicle. Referring to the inputs relating tocurrent task data 108 in FIG. 2, radio information 226 is determined byaccessing vehicle data regarding radio feature and function activity.Phone status 228 is determined by accessing existing vehicle datapertaining to an integrated cellular phone system. The values associatedwith the input data in FIG. 2 is input to a function. The function islocated in the driving workload estimator 102 and it utilizes the inputdata to determine the instantaneous workload estimate 110, theintermediate workload estimate 112 and the overall workload estimate114.

FIG. 3 is a table of logical operands associated with driving workloadestimation for use by a function to calculate a driving workloadestimate in an exemplary embodiment of the present invention. Thelogical operands are used to create a framework and to set initialweightings of the driving workload estimation and can be modified tofine tune the driving workload estimator 102. A workload estimate iscalculated to reflect an instantaneous workload estimate 110, anintermediate workload estimate 112 and an overall workload estimate 114based on assigning numeric values to each of the conditions depicted inFIG. 3. Numeric values and inputs can be the same for all three workloadestimates or they can vary. As shown in FIG. 3, the value of therelative workload effect associated with vehicle speed 202 can becalculated by assigning a numeric value to the results of applying thevehicle speed equations 302. A vehicle traveling between twenty milesper hour and fifty miles per hour can be given a higher speed value thana car traveling between zero miles per hour and twenty miles per hour.Similarly, a vehicle traveling between fifty miles per hour and seventymiles per hour can be given a higher speed value than a car travelingbetween twenty miles per hour and fifty miles per hour. A vehicletraveling over seventy miles per hour can be given a higher speed valuethan a car traveling between fifty miles per hour and seventy miles perhour. The value of the relative workload for turn signal status 204 canbe calculated by assigning a higher numeric value if the turn signal isactivated than if the turn signal is not activated, as reflected in theturn signal status equations 304. As shown in the ABS/TCS/stabilityequations 306, situations where the ABS, TCS and/or vehicle stabilitysystem are active can be given a higher value than when they are not.

Referring to FIG. 3, the value of the relative workload for externalconditions including headlamp status 214, wiper status 216, outside airtemperature 220 and time of day 224 can be calculated by assigningnumeric values to the results of applying the corresponding equations.Night can be given a higher relative value than day as reflected in theheadlamp status equations 308, precipitation can be given a higherrelative value than no precipitation and snow can be given a highernumeric value than rain as reflected in the wiper status equations 310and the outside air temperature equations 312. The relative valueassociated with time of day 224, as reflected in the time of dayequations 314, can be calculated by assigning higher numeric values asthe current time gets further away from noon and closer to midnight. Inan alternate embodiment, the value for time of day can be calculated asa sinusoidal cycle with the peak weighting from eleven p.m. to one a.m.and the baseline from noon to one p.m. The relative value associatedwith the radio information 226 can be calculated using the radio taskdata equations 316 where the act of manipulating the radio is given ahigher relative value than when no radio manipulation is taking place.Similarly, the relative workload value associated with phone status 228can be calculated by assigning a higher relative value to phone dialingand conversations than to the absence of phone activity. This isreflected in the phone status equations 318.

In an alternate embodiment of the present invention, information frommore than one input is utilized to create the workload estimates. Forexample, the workload estimate can take into account snowy roads if thetemperature is below freezing and the windshield wipers are turned on.Additionally, if the ABS brake system is activated then the estimate cantake into account the road conditions associated with snowy roads. Thesekinds of cross grouping combinations can lead to a better estimate ofthe driver workload. The time span that each value continues to becounted towards a driving workload estimate can depend on whether theworkload estimate is an instantaneous workload estimate 110, anintermediate workload estimate 112 or an overall workload estimate 114.For example, the function to calculate an intermediate workload estimate112 would continue to count the use of ABS or TCS for a specified periodof time (e.g., twenty seconds to one minute) while the function tocalculate the instantaneous workload estimate 110 would count the use ofABS or TCS for a shorter period of time (e.g., zero to three seconds).In this manner, the three types of workload estimates are created usingfunctions that weight the values assigned to the inequalities over aspecified time span. The resulting instantaneous workload estimate 110,intermediate workload estimate 112 and overall workload estimate 114 arethen output from the driving workload estimator 102. The output caninclude transmission to a specified location and logging to a specifiedlocation.

The disclosed invention provides the ability to estimate the workloadthat a driver is experiencing using data that is already availablewithin a vehicle. Vehicle data, environment data and current task datacan be used to create inferences about the driver's current state (i.e.,instantaneous workload estimate), short term state (i.e., intermediateworkload estimate) and long term state (i.e., overall workloadestimate). The workload estimates can be utilized by display functionsand controls within the vehicle to determine the timing of particularmessages and when to enable or disable particular functions. Forexample, a message to rotate the tires can be presented to the operatorof the vehicle when the workload estimate is on the low side and theoperator is more likely to be able to process the information. Havingthree time spans for the workload estimates provides the ability totrack the longer term effects of particular workload estimate elements.The ability to predict the driving workload simultaneously for differenttime spans can lead to better estimates of the driving conditions anddriver's state, resulting in better communication between driver andvehicle. Additionally, this informed interface may potentially result inhigher driver satisfaction with the vehicle and/or safer vehicleoperation.

As described above, the embodiments of the invention may be embodied inthe form of computer-implemented processes and apparatuses forpracticing those processes. Embodiments of the invention may also beembodied in the form of computer program code containing instructionsembodied in tangible media, such as floppy diskettes, CD-ROMs, harddrives, or any other computer-readable storage medium, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Anembodiment of the present invention can also be embodied in the form ofcomputer program code, for example, whether stored in a storage medium,loaded into and/or executed by a computer, or transmitted over sometransmission medium, such as over electrical wiring or cabling, throughfiber optics, or via electromagnetic radiation, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Whenimplemented on a general-purpose microprocessor, the computer programcode segments configure the microprocessor to create specific logiccircuits.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, the use of the terms first, second, etc. do not denoteany order or importance, but rather the terms first, second, etc. areused to distinguish one element from another.

1. A method for estimating workload placed on a driver of a vehicle, themethod comprising: receiving workload estimation data; calculating adriving workload estimate in response to said workload estimation dataand to previously received work load estimation data, said drivingworkload estimate including an instantaneous workload estimateindicative of current conditions, and one or more of an intermediateworkload estimate and an overall workload estimate indicative ofpreviously occurring conditions data; and outputting said drivingworkload estimate.
 2. The method of claim 1 wherein said workloadestimation data includes internally generated vehicle data.
 3. Themethod of claim 1 wherein said workload estimation data includesenvironment data.
 4. The method of claim 1 wherein said workloadestimation data includes current task data.
 5. The method of claim 1wherein said instantaneous workload estimate reflects the previous zeroto three seconds of vehicle operation.
 6. The method of claim 1 whereinsaid intermediate workload estimate reflects the previous three secondsto three minutes of vehicle operation.
 7. The method of claim 1 whereinsaid overall workload estimate reflects vehicle operation for the entireignition cycle.
 8. The method of claim 1 wherein said driving workloadestimate is expressed as a number ranging from one to ten.
 9. The methodof claim 1 wherein said driving workload estimate is expressed as anumber ranging from one to one-hundred.
 10. The method of claim 1wherein said calculating a driving work load estimate includes:assigning an instantaneous value to at least one of said workloadestimation data; applying an instantaneous workload function, whereininput to said instantaneous workload function includes each saidinstantaneous value and said applying results in the instantaneousworkload estimate; assigning an intermediate value to at least one ofsaid workload estimation data; applying an intermediate workloadfunction, wherein input to said intermediate workload function includeseach said intermediate value and said applying results in theintermediate workload estimate; assigning an overall value to at leastone of said workload estimation data; and applying an overall workloadfunction, wherein input to said overall workload function includes eachsaid overall value and said applying results in the overall workloadestimate.
 11. The method of claim 1 wherein said outputting includestransmitting said driving workload estimate to a specified location. 12.The method of claim 11 wherein said specified location is a vehicleinformation management system.
 13. The method of claim 1 wherein saidoutputting includes writing said driving workload estimate to a logfile.
 14. The method of claim 1 wherein said outputting is performed ona periodic basis.
 15. The method of claim 14 wherein said periodic basisless than one second.
 16. The method of claim 1 wherein said workloadestimation data includes at least one of vehicle speed, turn signalstatus, anti-lock brake status, traction control system status, vehiclestability data, steering wheel angle data, brake position data, throttleposition data, engine revolutions per minute, spark data and fuel data.17. The method of claim 1 wherein said workload estimation data includesat least one of headlamp status, wiper status, defroster status, outsideair temperature data, global positioning data and time of day.
 18. Themethod of claim 1 wherein said workload estimation data includes atleast one of radio information and phone status.
 19. The method of claim1 wherein said workload estimation data includes adaptive cruise controldata.
 20. The method of claim 1 wherein said workload estimation dataincludes at least one of forward collision warning data, side objectdetection data and rear collision warning data.
 21. The method of claim1 wherein said workload estimation data includes lane departure warningdata.
 22. The method of claim 1 wherein said workload estimation dataincludes driver identification data.
 23. A system for estimatingworkload placed on a driver of a vehicle, the system comprising: anetwork; and a microprocessor in communication with said network, saidmicroprocessor including instructions to implement the methodcomprising: receiving workload estimation data from said network;calculating a driving workload estimate in response to said workloadestimation data and to previously received workload estimation data,said driving workload estimate including an instantaneous workloadestimate indicative of current conditions, and one or more of anintermediate workload estimate and an overall workload estimateindicative of previously occurring conditions: and outputting saiddriving workload estimate.
 24. The system of claim 23 further comprisinga vehicle sensor in communication with said network for creating saidworkload estimation data.
 25. The system of claim 23 wherein saidnetwork is the Internet.
 26. The system of claim 23 wherein said networkis a wireless network.
 27. The system of claim 23 wherein saidoutputting said driving workload estimate includes transmitting saiddriving workload estimate to a receiving location over said network. 28.A computer program product for estimating workload placed on a driver ofa vehicle, the product comprising: a storage medium readable by aprocessing circuit and storing instructions for execution by theprocessing circuit for performing a method comprising: receivingworkload estimation data; calculating a driving workload estimate inresponse to said workload estimation data and to previously receivedworkload estimation data, said driving workload estimate including aninstantaneous workload estimate indicative of current conditions, andone or more of an intermediate workload estimate and an overall workloadestimate indicative of previously occurring conditions; and outputtingsaid driving workload estimate.
 29. A method for estimating workloadplaced on a driver of a vehicle, the method comprising: receivingworkload estimation data; calculating a driving workload estimate inresponse to said workload estimation data, said driving workloadestimate being indicative of current and previously occurringconditions, the calculating including: assigning an instantaneous valueto at least one of said workload estimation data; applying aninstantaneous workload function, wherein input to said instantaneousworkload function includes each said instantaneous value and saidapplying results in an instantaneous workload estimate; assigning anintermediate value to at least one of said workload estimation data;applying an intermediate workload function, wherein input to saidintermediate workload function includes each said intermediate value andsaid applying results in an intermediate workload estimate; assigning anoverall value to at least one of said workload estimation data; andapplying an overall workload function, wherein input to said overallworkload function includes each said overall value and said applyingresults in an overall workload estimate; and outputting said drivingworkload estimate.